层岩走向对偏压小净距隧道围岩稳定性分析

Stability Analysis of Bedrock Strike on the Surrounding Rock of Biased Small Clearance Tunnels

随着我国交通事业的不断推进,大量隧道需要穿越层岩地区,另一方面,偏压小净距隧道的施工也是近年来的难点。鉴于此,针对层状岩体在力学特性方面展现出来的各向异性,基于横观各向同性的节理岩体本构建立了有限元数值计算模型,对层岩走向与隧道轴向呈不同位置关系变化对围岩稳定性进行了对比分析。研究表明:①围岩变形主要集中在隧道拱顶沉降和仰拱隆起,拱顶沉降略大于仰拱隆起,由于左洞埋深大,左洞变形大于右洞变形。②层理的存在改变了围岩变形规律,围岩竖向位移增大,水平位移却得到了相应抑制。③围岩塑性区分布受岩层产状的影响明显,岩层走向与轴线平行时最大塑性应变最大,且在拱腰与拱脚处形成了类似“X”形的分布。④研究成果为类似工程的应用提供了一定的理论价值。

With the continuous development of China's transportation industry,numerous tunnels are required to traverse layered rock areas.Simultaneously,the construction of tunnels with narrow clearances presents a significant challenge.In light of this,considering the mechanical anisotropy exhibited by laminated rock bodies,a finite element numerical computational model is established based on the transverse isotropy of nodular rock bodies.This model facilitates a comparative analysis of the stability of surrounding rock along the axial direction of the tunnel under different positional relationships with laminated rock.The study reveals:①Surrounding rock deformation predominantly involves tunnel arch settlement and uplift,with arch settlement slightly exceeding uplift.Furthermore,the left tunnel experiences greater deformation than the right tunnel due to its deeper burial depth.②Laminations alter the deformation pattern of surrounding rock,resulting in increased vertical displacement but suppressed horizontal displacement.③The distribution of surrounding rock plastic zones is significantly influenced by rock layering,with maximum plastic strain occurring when rock layers are parallel to the axis,forming an X-shaped distribution at the arch waist and foot.④The research results provide some theoretical value for the application of similar projects.